The number one reason people buy a shoe is for the fit. Unfortunately, there is not a uniform standard for the fit of shoes. This means that a men's US 9.0 is not the same distance from heel to toe across manufactures. The shape of the shoe, commonly called the last, can also vary from manufacturer to manufacturer. Additionally, a single manufacturer may use more than one shape, which causes a difference in fit between shoes within the same manufacturer.
It is presently difficult for a consumer to determine how one shoe will fit compared to another without trying on the shoes. Accordingly, when shoes are sold on the internet or through a catalog, consumers frequently return shoes after trying them on at home due to a poor fit. This has created a high return rate for online retailers.